Field of the Invention
The present invention relates to a needle assembly for an injection device, in particular a needle assembly to be used in combination with a container comprising a product to be injected, said needle assembly comprising a safety system for protecting the needle before and after use, the needle assembly allowing obtaining a very compact injection device.
Description of Related Art
In this application, the distal end of an element or of a device means the end furthest away from the hand of the user and the proximal end means the end closest to the hand of the user, when the element or device is in the use position. Similarly, in this application, the terms “in the distal direction” and “distally” mean in the direction of the injection, and the terms “in the proximal direction” and “proximally” mean in the direction opposite to the direction of injection.
In this application, the terms “radially”, “outwardly” and “inwardly” are intended to mean radially, outwardly and inwardly with respect to the longitudinal axis of the needle assembly and injection device of the invention.
Injection devices, such as syringes, are well known. Many different types of injection devices have been designed for administering medicines. Injection devices usually comprise a container intended to receive the product to be injected and a plunger rod intended to move a stopper within the container so as to expel the product therefrom at the time of injection. Empty and pre-filled disposable injection devices exist but prefilled devices are now preferred because they are convenient, safe and efficient and may be used directly in emergency cases.
Usually, in addition to these elements, it is preferred that the injection device further comprises a safety system for protecting the needle, and in particular for protecting its distal sharp tip, before and after use of the injection device, in other words before the injection and after the injection. It is also preferred that such safety system be triggered automatically after the end of the injection, with no additional operation required from the user, in order to ensure the safety of said user. Safety systems usually are provided under the form of sleeves intended to cover the needle at the end of injection, the presence of such sleeves usually increasing the volume and the overall length of the injection device.
Moreover, prefilled injections devices are usually filled by a pharmaceutical company, packaged for use, and then typically stored at a doctor's office, hospital, etc. until they are needed for use. In such conditions, the prefilled injection device occupies a predetermined amount of storage space based upon the size of the injection device (typically comprising a syringe barrel, a stopper, a plunger rod, and possibly a needle, and a safety system). In some cases, the predetermined amount of storage space the injection device will occupy is a maximum space approximating the length of the plunger rod, plus the length of the syringe barrel, plus the length of the needle (if provided).
Required storage space is an important feature for prefilled injection devices. It is especially important when the medicine contained in these devices must be stored and transported at low temperatures. Storage of these injection devices may require refrigeration and can be expensive. This is especially the case in hospitals and pharmacies, where storage space for medicines is limited.
Thus, there is a need for an injection device which would be particularly compact, particularly when the injection device is prefilled, and that would nevertheless protect the user from accidental needlestick injuries before use and after use. There is therefore still a need for a needle assembly comprising a safety system, said needle assembly requiring less space as possible.
Moreover, such an injection device must be simple to use, and preferably would not alter the typical process followed by the medical staff when administering an injection.